PROJECT SUMMARY/ABSTRACT There is a fundamental gap in understanding the specific speech contexts in which perception predicts production in children with speech sound disorder (SSD). This gap critically hampers our ability to design efficacious treatments for these children. The long-term goal is to specify how speech perception impacts speech production in children with SSD, and to contribute to the development of evidence-based assessment and intervention for these children. The overall objective of this application is to learn how perception of systematically-varied consonantal contrasts in different contexts predicts and facilitates speech production in 4- and 5-year old children with different profiles of SSD. The central hypothesis is that children with SSD and concomitant language impairment (LI) have less detailed underlying phonological representations in general than children with SSD-only; we expect children with SSD+LI to experience difficulties perceiving a wide range of consonantal contrasts, whereas children with SSD-only are expected to have difficulties perceiving only the specific contrasts that they misarticulate. The rationale for the proposed research is that it is expected to provide essential preliminary data for a larger scale determination of the impact of speech perception intervention on speech production learning. Guided by preliminary data, this hypothesis will be tested by pursuing three specific aims: 1) Determine how discrimination of word-medial consonantal contrasts predicts speech production and language abilities of three groups of children (typically developing, SSD-only, SSD+LI); 2) Determine the profile of mispronunciation detection skills of consonants in multiple word positions by these three groups of children; and 3) Reveal how mispronunciation detection training with self-produced words influences speech production in children with SSD-only and children with SSD+LI. For the first aim, identification of systematically varied word-medial consonantal contrasts will be compared across the three groups of participants. For the second aim, mispronunciation detection abilities of consonants in multiple word positions will be compared across the three groups of children. Under the third aim, we will compare speech perception training focused on judging the accuracy of their own speech or the accuracy of multiple talkers in children with SSD-only and children with SSD+LI. This approach is innovative because novel focus on word- medial consonants will bring new insights as well as encourage generalization from clinic to natural conversational settings. In addition, by systematically investigating perception of consonantal contrasts in different contexts, our approach has enhanced potential to identify specific speech perception deficits in children with SSD-only and children with SSD+LI. Proposed studies are significant because they will clarify contributions of speech perception to development of speech production in children with SSD with or without concomitant LI. Ultimately, such knowledge will lead to improved evaluation and treatment of SSD.